Orthodontic devices and appliances are used to correct malocclusions and anomalies of tooth position.
If such devices and appliances are of arcylate- or methacrylate-based plastic, they can be produced by the application of powdered polyacrylate or polymethacrylate and a liquid monomer, typically methylmethacrylate, to plaster casts using the drip method or spraying or casting and by subsequent polymerization at an elevated temperature and under pressure.
Dental prostheses, orthodontic appliances and the like which comprise a plurality of plastic plates are well known, for example the process wherein they are shaped by deep drawing methods and disposed in several layers on top of one another, joined together by layers of adhesive, is described in German Utility Model No. DE-GM 6 753 339 (1968).
A method used in prosthodontics to produce tooth replacements is that of applying polymerizable material in layers to a plaster mold and polymerizing it by heating, exposing it to visible or ultraviolet light or some other means, (see for example German Patent DE-PS 1 516 456 and corresponding British Patent Specification No. 1,115,544 and German Patent Disclosure Document No. DE-OS 2 910 077 and corresponding U.S. Pat. No. 4,267,133).